Organic compounds having a positive charge are known to exhibit antibacterial properties, regardless of whether they are low molecular weight compounds or high molecular weight compounds. The application technology utilizing such properties has spread widely from the medical field to general clothing. For example, quaternary ammonium compounds such as benzalkonium chloride or the like are soluble in water, and so are in themselves used as sterilizing or disinfecting solutions. Conversely, however, since they are soluble in water, the range of usage as antibacterial agents is limited.
Further, anionic groups are introduced to the surface of synthetic polymer articles and then treatment with quaternary ammonium bases is performed so as to obtain a material maintaining an antibacterial property over a sustained long term period. The resulting material is used as a filter material for air filters and dialysis. This technique is also applied to textile materials, and utilized for clothing having antibacterial properties and agents for protecting wound.
As a means of introducing quaternary ammonium to the surface of a polymer material to obtain a material exhibiting sustained antibacterial properties, for example, Japanese Published Unexamined Patent Application No. 54-86584 describes a method for bringing a polymer obtained by polymerizing an acidic-group-containing monomer into contact with an aqueous solution of a quaternary ammonium base. Further, Japanese Published Unexamined Patent Application No. 59-164342 discloses a method for introducing an anionic-group-containing vinyl monomer to the surface of a synthetic polymer article by graft polymerization or the like, and then treating by a quaternary ammonium base.
In the conventional methods, however, the rate of introduction of the quaternary ammonium base for manifesting the antibacterial property was not necessarily sufficient and a satisfactory sustenance could not be obtained. Further, the process of production was also complicated.
The present inventors engaged in intensive research with the object of obtaining a material having a sustained antibacterial action and having the property of insolubility in solvents (especially water) while maintaining the antibacterial property of a positively charged organic compound, and discovered that the objects can be achieved by a polyelectrolyte complex obtained by reacting a specific anionic polymer and a specific cationic polymer. The present invention is based on the above discovery.